Seen on Windows buildbot:
'test_aifc' left behind file '@test' and it couldn't be removed: [Error
32] The process cannot access the file because it is being used by
another process: '@test'
This is because Aifc_read.close() does not close the underlying file.

Sorry, but the problem still exists.
self._file is a chunk.Chunk object, and its close() method does nothing.
Adding "self.file = None" at the end of chunk.Chunk.close() helps, even
if this relies on reference counting to close the file.